Lettuce variety ‘PRO 1632’

ABSTRACT

New lettuce variety designated ‘PRO 1632’ is described. ‘PRO 1632’ exhibits stability and uniformity.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit under 35 § USC 119(e) of prior U.S.Provisional Patent Application No. 62/307,243, filed Mar. 11, 2016, thedisclosure of which is hereby incorporated by reference in its entirety.

FIELD

This invention relates to the field of plant breeding. In particular,this invention relates to new lettuce, Lactuca sativa, variety ‘PRO1632’.

BACKGROUND

Lettuce is an increasingly popular crop. Worldwide lettuce consumptioncontinues to increase. As a result of this demand, there is a continuedneed for new lettuce varieties. In particular, there is a need forimproved green leaf and iceberg lettuce varieties that exhibit improvedgrowth habits, bolting and tip burn tolerance, and disease resistance.

SUMMARY

In order to meet these needs, the present invention is directed toimproved lettuce varieties.

In one embodiment, the present invention is directed to an improvediceberg lettuce variety that exhibits vigorous growth, increased weightand yield. In one embodiment, the present invention is directed tolettuce, Lactuca sativa, seed designated as ‘PRO 1632’ having ATCCAccession Number PTA-124209. In one embodiment, the present invention isdirected to a Lactuca sativa lettuce plant and parts isolated therefromproduced by growing ‘PRO 1632’ lettuce seed. In another embodiment, thepresent invention is directed to a Lactuca sativa plant and partsisolated therefrom having all the physiological and morphologicalcharacteristics of a Lactuca sativa plant produced by growing ‘PRO 1632’lettuce seed having ATCC Accession Number PTA-124209. In still anotherembodiment, the present invention is directed to an F₁ hybrid Lactucasativa lettuce seed, plants grown from the seed, and a head isolatedtherefrom having ‘PRO 1632’ as a parent, where ‘PRO 1632’ is grown from‘PRO 1632’ lettuce seed having ATCC Accession Number PTA-124209.

Lettuce plant parts include lettuce heads, lettuce leaves, parts oflettuce leaves, pollen, ovules, flowers, and the like. In anotherembodiment, the present invention is further directed to lettuce heads,lettuce leaves, parts of lettuce leaves, flowers, pollen, and ovulesisolated from ‘PRO 1632’ lettuce plants. In another embodiment, thepresent invention is further directed to tissue culture of ‘PRO 1632’lettuce plants, and to lettuce plants regenerated from the tissueculture, where the plant has all of the morphological and physiologicalcharacteristics of ‘PRO 1632’ lettuce plants.

The present invention is further directed to a method of selectinglettuce plants by: a) growing more than one ‘PRO 1632’ lettuce plant,where the plants are grown from lettuce seed having ATCC AccessionNumber PTA-124209; and b) selecting a plant from step a). The presentinvention is further directed to lettuce plants and seeds producedtherefrom, where the lettuce plants and seeds are isolated by theselection method of the invention.

In another embodiment, the present invention is further directed to amethod of breeding lettuce plants by crossing a lettuce plant with aplant grown from ‘PRO 1632’ lettuce seed having ATCC Accession NumberPTA-124209. In still another embodiment, the present invention isfurther directed to lettuce plants, lettuce parts from the lettuceplants (e.g., lettuce heads), and seeds produced therefrom where thelettuce plant is isolated by the breeding method of the invention.

DETAILED DESCRIPTION Definitions

In order to more clearly understand the invention, the followingdefinitions are provided:

Green Leaf Lettuce: Green leaf lettuce is Lactuca sativa L. The plantdevelops in an upright open growing habit with medium textured leaves.The leaves are typically somewhat savoyed, while the shape can vary byvariety. Leaf margins are often undulated, lobed or frilled. Otherleaves range in color from light green to dark green with a minimalmidrib. Inner heart leaves are typically smaller and lighter green incolor.

Iceberg Lettuce: Iceberg lettuce, Lactuca sativa L. var. capitata L. isalso known as ‘crisp head’ lettuce. Iceberg lettuce is a lettuce planttype that forms a firm, spherical head formed with tightly foldedbrittle textured foliage. Internal color ranges from white to yellow tolight green. The wrapper leaves surrounding the head are wider than theyare long. Leaf margins can vary by type, being entire, undulating, orfrilled. Wrapper leaf color ranges from yellow green to dark green.

Core Length: Core length is the length of the internal lettuce stem.Core length is measured from the base of the cut head to the tip of thecore.

Core Diameter: Core diameter is the diameter of the lettuce stem at thebase of the cut head.

Green Leaf Heart: Green leaf heart is the densest part of the Green Leafplant, and is often yellow and light green in color and of succulenttexture. The heart is generally enclosed by two to three outer darkergreen leaves.

Heart Length: Heart length is the length of the vertically slicedlettuce plant as measured from the base of the cut stem to the top leafmargin of the longest outermost leaf that encloses the green leaf heart.

Head Length: Core Length Ratio: The ratio of the head length to corelength is indicative of the percentage of useable product produced bythe lettuce plant.

Plant Diameter: The plant diameter is a measurement across the top ofthe lettuce plant at its widest point. The measurement of frame diameteris taken from the outer most leaf tip horizontally to the outer mostleaf tip.

Head Diameter: Head diameter is the diameter of the vertically slicedlettuce plant head at its widest horizontal point, perpendicular to thestem.

Head Length: Head length is the diameter of the vertically slicedlettuce plant head as measured from the base of the cut stem to the capleaf.

Average Head Diameter: Average head diameter is an average of themeasured head diameter and head length of the lettuce head.

Average Head Diameter: Core Length Ratio: The ratio of the average headdiameter to core length is indicative of the percentage of useableproduct produced by the lettuce plant.

Frame Diameter: The frame diameter is a measurement of the lettuce plantdiameter at its widest point. The measurement of frame diameter is fromthe outer most wrapper leaf tip to outer most wrapper leaf tip.

Head Weight: Head weight is the weight of the marketable lettuce plant,cut and trimmed to market specifications.

Rogueing: Rogueing is the process in lettuce seed production whereundesired plants are removed from a variety. The plants are removedbecause they differ physically from the general desired expressedcharacteristics of the variety. The differences can be related to size,color, maturity, leaf texture, leaf margins, growth habit, or any othercharacteristic that distinguishes the plant.

Market Stage: Market stage is the stage when a lettuce plant is readyfor commercial lettuce harvest. In the case of a romaine lettucevariety, a romaine plant is at a marketable state when the heart hassome density and the head has reached an adequate size and weight.

Tomato Bushy Stunt: Lettuce dieback was first observed in California inthe mid-1980s, and reports of the disease have increased over the last10 years. Complete crop losses have occurred in fields of Green Leaflettuce, and no commercial Green Leaf cultivar has been shown to beresistant to the disease. In the U.S., Green Leaf is a rapidly growingmarket segment, having increased 68% over the last five years (USDA,2002). The disease has occurred in commercial fields of some leaflettuce cultivars; however, symptoms have never been observed on anymodern crisphead (iceberg) cultivars. Lettuce dieback is caused byseveral related tombusviruses including tomato bushy stunt virus (TBSV)and lettuce necrotic stunt virus (LNSV) (Liu et al., 1999; Obermeier etal., 2001). These are soil-borne, highly stable, and mechanicallytransmitted, and have no known vector. The conditions affecting symptomdevelopment remain poorly understood. The disease is frequently observedin low-lying areas of fields with a prior history of flooding,suggesting that the virus may be carried in river water and/or thatdisease symptoms may be associated with increased root stresses such asthose presented by excess moisture. No effective cultural or chemicalcontrol methods have yet been identified.

Resistance to Tomato Bushy Stunt refers to a level of resistance in alettuce variety as measured by visual symptoms. Resistance is deemedpresent when symptoms are not present in at least 95% of a lettucevariety when exposed to tomato bushy stunt virus (TBSV).

Taking into account these definitions, the present invention is directedto seeds of the lettuce variety ‘PRO 1632’, plants produced by growing‘PRO 1632’ lettuce seeds, heads isolated or harvested from the plants,one or more plants selected from a collection of ‘PRO 1632’ plants andseeds derived or produced therefrom; plants produced by crossing alettuce plant with a ‘PRO 1632’ lettuce plant and seeds derived orproduced therefrom.

Objective Description of the Variety ‘PRO 1632’

‘PRO 1632’ is an iceberg lettuce variety that is larger heading,resistant to tip burn and bolting, and is suitable for plantings inregions such as the southern Salinas valley in California, and Yuma,Ariz.

Through extensive field trialing and screenings, ‘PRO 1632’ hasdemonstrated to have a large heading, resistance to tip burn andbolting, and to be well adapted for summer plantings in regions such asthe southern Salinas valley, California and spring plantings in regionssuch as Yuma, Ariz.

‘PRO 1632’ was evaluated in multiple trials and evaluated for improvedsize, improved weight, improved frame size, and improved tolerances totip burn and bolting.

As evaluated in multiple seed production fields and commercialplantings, ‘PRO 1632’ has been observed to be uniform and stable withoutvariants.

As described herein, lettuce variety ‘PRO 1632’ has numerousdistinguishing characteristics.

A. Variety Description Information

Plant Type: Iceberg Seed: Seed Color: Black Light Dormancy: No HeatDormancy: Yes Cotyledons: Shape of Cotyledons: Intermediate Shape ofFourth Leaf: Spatulate Length/Width Index of Fourth Leaf: 26 ApicalMargin: Moderately Dentate Basal Margin: Moderately Dentate Undulation:Medium Green Color: Medium Anthocyanin: Absent Distribution: NoneRolling: Absent Cupping: Uncupped Reflexing: Slight Mature Leaves:Margin: Incision Depth (Deepest penetration Moderate of the margin):Indentation (Finest Division of the Crenate Margin): Undulation of theApical Margin: Moderate Green Color: Medium Anthocyanin Distribution:None Size: Large Glossiness: Moderate Blistering: Slight Leaf Thickness:Thick Trichomes: AbsentB. Comparison to Most Similar Variety

Characteristic PRO 1632 PX 1565 Spread of Frame Leaves   42 cm   35 cmHead Diameter (market trimmed with   16 cm   13 cm single cup leaf) HeadShape Spherical Spherical Head Size Class Large medium Head Count perCarton 24 24 Head Weight 1030 840 Head Firmness Firm Firm Butt ShapeRounded Rounded Midrib Flat Flat Core (Stem of Market-trimmed Head)Diameter at the base of the Head  3.0 cm  4.0 cm Ratio of HeadDiameter/Core 5.33 3.25 Diameter Core Height from base of Head to  5.0cm  4.0 cm Apex Number of Days from First Water 75 71 Date to Seed StalkEmergence (Summer condition) Bolting Class Medium Slow Height of MatureSeed Stalk  138 cm  131 cm Spread of Bolter Plant   42 cm   38 cm BolterLeaves Curved Curved Margin Dentate Dentate Color Dark Green Dark GreenBolter Habit Terminal Inflorescence Present Present Lateral Shoots(above head) Absent Absent Basal Side Shoots Absent Absent AdaptationRegions Salinas Salinas Valley, CA Valley, CA Yuma, AZ.C. Growing Season

Season ‘PRO 1632’ ‘Salute’ Spring area Salinas Valley, CA DesertSouthwest Summer area Salinas Valley, CA Salinas Valley, CA Fall areaNot Adapted Not Adapted Winter area: Not Adapted Not AdaptedD. Diseases and Stress Reactions

Disease or Stress ‘PRO 1632’ ‘Salute’ Virus Big Vein: SusceptibleSusceptible Lettuce Mosaic: Susceptible SusceptibleE. Fungi/Bacteria

Fungal/Bacterial ‘PRO 1632’ ‘Laguna Fresca’ Corky Root Rot (PythiumSusceptible Susceptible Root Rot): Downy Mildew (Races I, SusceptibleSusceptible IIA, III): Powdery Mildew: Susceptible SusceptibleSclerotinia Rot: Intermediate Intermediate Bacterial Soft RotSusceptible Susceptible (Pseudomonas spp. & others): Not tested Botrytis(Gray Mold): Susceptible Susceptible Other: Corky Root Rot SusceptibleSusceptible (Rhizomonas suberifaciens):F. Insects

Insects ‘PRO 1632’ ‘Laguna Fresca’ Cabbage Loopers: SusceptibleSusceptible Root Aphids: Susceptible Susceptible Green Peach Aphid:Susceptible SusceptibleG. Physiological/Stress

Stress ‘PRO 1632’ ‘Laguna Fresca’ Tipburn Resistant Resistant HeatResistant Resistant Drought Susceptible Susceptible Cold SusceptibleSusceptible Salt Susceptible SusceptibleH. Post Harvest

Characteristic ‘PRO 1632’ ‘Laguna Fresca’ Pink Rib ModeratelySusceptible Moderately Susceptible Russet Spotting ModeratelySusceptible Moderately Susceptible Rusty Brown Moderately SusceptibleModerately Susceptible Discoloration Internal Rib Moderately SusceptibleModerately Susceptible Necrosis (Blackheart, Gray Rib, Gray Streak)Breeding and Selection

The present invention is further directed to the use of the ‘PRO 1632’lettuce variety in breeding and selection of new varieties.

A. Breeding

In lettuce breeding, lines are selected for their appropriatecharacteristics. For example, one line may be selected for bolttolerance in the fall growing conditions of the desert productionlocations of California and Arizona. Another line may be selected forthe size, color, and texture of the lettuce head. Crosses are made, forexample, to produce a dark green, sure heading iceberg lettuce withimproved texture, and size for fall plantings in Yuma, Ariz. and Huron,Calif.

To optimize crossing, it is important to note that lettuce is anobligate self-pollinating species. This means that the pollen is shedbefore stigma emergence, assuring 100% self-fertilization. Since eachlettuce flower is an aggregate of about 10-20 individual florets(typical of the Compositae family), manual removal of the anther tubescontaining the pollen is performed by procedures well known in the artof lettuce breeding.

The manual removal of anther tubes, though an effective means to ensurethe removal of all self pollinating possibilities, is very tedious andtime consuming when a large number of crosses are to be made. Thebreeders have therefore adapted a well documented and modified method ofmaking crosses more efficiently using these methods. This particularcross was made by first misting the designated male flowers to wash thepollen off prior to fertilization. This process of misting is a provenand effective means of pollen removal that assures crossing orhybridization. About 60-90 minutes past sunrise, flowers to be used forcrossings are selected. The basis for selection are open flowers, withthe stigma emerged and the pollen visibly attached to the single stigma(about 10-20 stigma). Using 3-4 pumps of water from a regular spraybottle, the pollen is washed off with enough pressure to dislodge thepollen grains, but not enough to damage the style. Excess water is driedoff with clean paper towels. About 30 minutes later, the styles shouldspring back up and the two lobes of the stigma are visibly open in a “V”shape. Pollen from another variety or donor parent is then introduced bygently rubbing the stigma and style of the donor parent to the maternalparent. Tags with the pertinent information on date and pedigree arethen secured to the flowers in order to keep track.

About 2-3 weeks after pollination, seeds are harvested when theinvolucre have matured. The seeds are eventually sown and in thepresence of markers such as leaf color or leaf margins, the selfed ormaternal seedlings or plants are identified. Generally, there are novisible markers and breeders must wait until the F₂ generations whenexpected segregation patterns for the genetic character of interest canbe followed. This latter situation mandates a lengthy wait to determineif hybrids are produced. Two relevant references teaching methods forout crossing lettuce are: (1) Ryder, E. J. and A. S. Johnson. 1974. Mistdepollination of lettuce flowers. Hortscience 9:584; and (2) Nagata, R.T. 1992. Clip and Wash Method of Emasculation for Lettuce. Hortscience27(8):907-908 both of which are hereby incorporated by reference intheir entirety for the purpose of providing details on the techniqueswell known in the art.

B. Selection

In addition to crossing, selection may be used to identify and isolatenew lettuce lines. In lettuce selection, lettuce seeds are planted, theplants are grown and single plant selections are made of plants withdesired characteristics. Such characteristics may include improved headand frame size, deeper or darker green leaf color, etc. Seed from thesingle plant selections are harvested, separated from seeds of the otherplants in the field and re-planted. The plants from the selected seedare monitored to determine if they exhibit the desired characteristicsof the originally selected line. Selection work is continued overmultiple generations to increase the uniformity of the new line.

Deposit Information

A deposit of the lettuce variety ‘PRO 1632’ is maintained by ProgenyAdvanced Genetics, having an address at 590A Works Street, Salinas,Calif. 93901, United States of America. Access to this deposit will beavailable during the pendency of this application to persons determinedby the Commissioner of Patents and Trademarks to be entitled theretounder 37 C.F.R. § 1.14 and 35 U.S.C. § 122. Upon allowance of any claimsin this application, all restrictions on the availability to the publicof the variety will be irrevocably removed by affording access to adeposit of at least 2,500 seeds of the same variety made according tothe Budapest Treaty in the American Type Culture Collection (ATCC), ATCCPatent Depository, 10801 University Boulevard, Manassas, Va., 20110,USA.

The lettuce variety ‘PRO 1632’ was deposited on Jun. 6, 2017 accordingto the Budapest Treaty in the American Type Culture Collection (ATCC),ATCC Patent Depository, 10801 University Boulevard, Manassas, Va.,20110, USA. The deposit has been assigned ATCC number PTA-124209. Accessto this deposit will be available during the pendency of thisapplication to persons determined by the Commissioner of Patents andTrademarks to be entitled thereto under 37 C.F.R. § 1.14 and 35 U.S.C. §122. Upon allowance of any claims in this application, all restrictionson the availability to the public of the variety will be irrevocablyremoved.

The deposit will be maintained in the ATCC depository, which is a publicdepository, for a period of at least 30 years, or at least 5 years afterthe most recent request for a sample of the deposit, or for theeffective life of the patent, whichever is longer, and will be replacedif a deposit becomes nonviable during that period.

This invention will be better understood by reference to the followingnon-limiting Examples.

EXAMPLES Example 1: General Trialing Method

The following steps illustrate the general trialing method of theinvention:

I. Set Up

-   1. A trial is set up to compare one or more lines. Parental lines    and related varieties are identified.-   2. Primary slots are identified.-   3. Necessary accession lines are located and purchased/received from    seed dealers or growers.-   4. All varieties are assigned a number to maintain integrity and    anonymity.-   5. Trials are set up in with all necessary varieties. Variety    arrangement for trial is diagramed.

II. Planting

-   1. Commercial plantings are located by contacting commercial growers    during the planting slot recommended for the variety.-   2. A field is located during commercial planting and the necessary    rows and area is marked off.-   3. Varieties are planted according to a diagram, generally in 100    foot ranges.-   4. All varieties are planted in same manner to mimic the planting of    the commercial variety as closely as possible.-   5. A trial map is drawn diagramming the trial, the trial location in    the field and directions to the field.

III. Maintenance

-   1. All varieties are treated identically. Plants are watered,    fertilized, and treated to control pests in the same manner as other    lettuce plants in the commercial field.-   2. The trial is thinned to separate the plants for optimum growth.

IV. Evaluation

-   1. Evaluations are done as near to the time of the commercial    harvest as possible.-   2. The evaluation is conducted “blindly”. The evaluator(s) do not    have the key to the trial at the time of evaluation.-   3. 24 heads of each variety are evaluated.    -   a. The frame diameters of 24 random plants are measured to the        nearest cm.    -   b. 24 mature plants of each variety are cut to the cap leaf.    -   c. The following measurements are then conducted and recorded:        -   1. Each plant is weighed to the nearest gram.        -   2. The core diameter of each head is measured to the nearest            mm.        -   3. The heads are then sliced in to halves, discarding 1 half        -   4. The core lengths (from the cut stem to the core tip) are            measured to the nearest mm.        -   5. The plant length (from the cut stem to the cap leaf) is            measured to the nearest mm.        -   6. The plant diameter (at its widest point) is measured to            the nearest mm.        -   7. The heart length is measured to the nearest mm.        -   8. The ideal maturity or harvest date is then estimated            based on the solidity of the plant, the core length and any            other physiological characteristics present.        -   9. The leaf color is documented using the Munsell Color            Charts for Plant Tissue.    -   e. From these measurements, an Excel program is used to        calculate the averages, the standard deviations and the T-Tests        for the compared varieties.

Example 2: Comparative Analysis

Following the procedures of Example 1, ‘PRO 1632’ iceberg lettuce wascompared to its closest variety, ‘PX 1565’.

‘PRO 1632’ is a new and distinct variety of iceberg lettuce that mostclosely resembles the variety ‘PX 1565’. ‘PRO 1632’ is a Salinas-typeiceberg lettuce variety adapted to cooler lettuce production regionssuch as the Salinas valley of California. ‘PRO 1632’ is a larger headingand large framed variety, with excellent heading characteristics, headshape, and leaf texture. ‘PRO 1632’ is larger heading and framed than‘PX 1565’, and has a black seed color, whereas ‘PX 1565’ is white.

Although the foregoing invention has been described in some detail byway of illustration and examples for purposes of clarity andunderstanding, it will be obvious that certain modifications andalternative embodiments of the invention are contemplated which do notdepart from the spirit and scope of the invention as defined by theforegoing teachings and appended claims.

What is claimed:
 1. A Lactuca sativa seed designated as ‘PRO 1632’,representative sample of seed having been deposited under ATCC AccessionNumber PTA-124209.
 2. A Lactuca sativa plant produced by growing theseed of claim
 1. 3. A plant part from the plant of claim
 2. 4. The plantpart of claim 3, wherein said part is a head, a leaf, or a portionthereof.
 5. The plant part of claim 4, wherein said part is a head.
 6. ALactuca sativa plant having all the physiological and morphologicalcharacteristics of the Lactuca sativa plant of claim
 2. 7. A plant partfrom the plant of claim
 6. 8. The plant part of claim 7, wherein saidpart is a head, a leaf, or a portion thereof.
 9. The plant part of claim8, wherein said part is a head.
 10. An F₁ hybrid Lactuca sativa planthaving ‘PRO 1632’ as a parent where ‘PRO 1632’ is grown from the seed ofclaim
 1. 11. A pollen grain or an ovule of the plant of claim
 2. 12. Atissue culture of the plant of claim
 2. 13. A lettuce plant regeneratedfrom the tissue culture of claim 12, wherein the plant has all of themorphological and physiological characteristics of a lettuce plantproduced by growing seed designated as ‘PRO 1632’, representative sampleof seed having been deposited under ATCC Accession Number PTA-124209.14. A method of making lettuce seeds, said method comprising crossingthe plant of claim 2 with another lettuce plant and harvesting seedtherefrom.
 15. A method of selecting lettuce variety ‘PRO 1632’,comprising: a. growing more than one plant from the seed of claim 1; andb. selecting a plant from step a).
 16. A Lactuca sativa plant selectedby the method of claim
 15. 17. Lactuca sativa seed produced from theLactuca sativa plant of claim 16.